Findings--Friends use the city similarly, and you have a higher chance of running into a friend if you live in the suburbs. Method--mapping ellipse-shaped polygons of where people make/receive calls in Jiamusi China, and those of his or her phone call friends. Good for--if you have a geolocated social network and you want to learn more about who uses which parts of the city, and whether the city is set up for friendships.